Suing or threatening to sue people is definitely bad publicity and had minimum effect, as this was also demonstrated in the long fight of the music industry against individual P2P? users. Still, the music industry kept fighting and fighting over a battle that was lost even before it began, one of the reasons being that there was no real possibility for recovering the lost profits from the defendants. I think that RIAA was aware of that, and what they did had as its sole purpose to scare P2P? users, since the exponential increase of unauthorized copyrighted material on the net was killing their business at an extremely rapid pace. Their response, I guess was fueled by panic, not by reason. Perhaps the rapid increase in market share for OSS in the future may, in turn, lead Microsoft panic and start suing big developers of OSS.

In the aforementioned analogy, however, there is one major difference between illegal music file sharing and developing OSS. In the first case, a lawsuit has no other impact but to the person being sued. In the case of OSS, a potential threat to an OSS developer means subsequent trouble for all the end users of the program developed by that developer. The effects of such lawsuits therefore are systemic, and even unpredictable, as they usually extend beyond the software industry, into the industries in which the end-users of OSS are active. So the question for Microsoft becomes a matter of figuring out how many enemies would such a lawsuit create, and whether it is in a position to fight such a battle. Considering that OSS is currently being used by major players in sectors ranging from financial services through manufacturing and distribution to the public sector, it seems highly unlikely that Microsoft would like to fight in so many fronts. After all, many of these companies that use OSS may be Microsoft's shareholders!